SQL to JSON - Create a Json Array - json

Question

I have the below data:
CREATE TABLE mytable
(
ID int,
Product nvarchar(50),
Usage nvarchar(255),
);
INSERT INTO mytable VALUES (99346,'Universal light','Art and Culture');
INSERT INTO mytable VALUES (99346,'Universal light','Health and Care');
INSERT INTO mytable VALUES (99346,'Universal light','Hotel and Wellness');
INSERT INTO mytable VALUES (99346,'Universal light','Education and Science');
And I have created the following code to get my JSON output:
SELECT DISTINCT T1.ID
,T1.Product
,(SELECT T2.Usage
FROM mytable T2
WHERE T1.ID=T2.ID
FOR JSON PATH) as 'Usage'
FROM mytable T1
FOR JSON PATH
It outputs the following results:
[
{
"ID": 99346,
"Product": "Universal light",
"Usage": [
{
"Usage": "Art and Culture"
},
{
"Usage": "Health and Care"
},
{
"Usage": "Hotel and Wellness"
},
{
"Usage": "Education and Science"
}
]
}
]
I would like to have the results as below, but can't figure out how to change the syntax:
[
{
"ID": 99346,
"Product": "Universal light",
"Usage": [ "Art and Culture" , "Health and Care" , "Hotel and Wellness" , "Education and Science"
]
}
]
Any help on this much appreciated.
EDIT
If I use this initial data, where at the end of line 3 I have an extra ' ' the solution does not work, no error or warning:
INSERT INTO mytable VALUES (99346,'Universal light','Art and Culture');
INSERT INTO mytable VALUES (99346,'Universal light','Education and Science');
INSERT INTO mytable VALUES (99346,'Universal light','Health and Care ');
INSERT INTO mytable VALUES (99346,'Universal light','Hotel and Wellness');
INSERT INTO mytable VALUES (99346,'Universal light','Offices and Communication');
INSERT INTO mytable VALUES (99346,'Universal light','Presentation and Retail');
I have tried to use TRIM, as you can see below:
SELECT Distinct ID
,Product
,json_query(QUOTENAME(STRING_AGG('"' + STRING_ESCAPE(TRIM(Usage), 'json') + '"', char(44)))) AS 'Usage'
FROM mytable
GROUP BY ID
,Product
FOR JSON PATH;
Unfortunately it does not work and the whole array 'Usage' is somehow ignored, see results:
[
{
"ID": 99346,
"Product": "Universal light"
}
]

Answer 1

You can use STRING_AGG to build the array like this:
SELECT DISTINCT ID
,Product
,json_query(QUOTENAME(STRING_AGG('"' + STRING_ESCAPE(Usage, 'json') + '"', char(44)))) AS 'Usage'
FROM mytable T1
GROUP BY ID
,Product
FOR JSON PATH;
If you are not using SQL Sever 2017 or later, you can use concatenate the values using XML PATH.
SELECT DISTINCT T1.ID
,T1.Product
,
(
'[' +
STUFF
(
(
SELECT ',' + '"' + T2.Usage + '"'
FROM mytable T2
WHERE T1.ID=T2.ID
FOR XML PATH, TYPE
).value('.', 'NVARCHAR(MAX)')
,1
,1
,''
)
+ ']'
) as 'Usage'
FROM mytable T1
FOR JSON PATH
For your edit use:
SELECT Distinct ID
,Product
,json_query('[' + (STRING_AGG('"' + STRING_ESCAPE(TRIM(Usage), 'json') + '"', char(44))) + ']') AS 'Usage'
FROM mytable
GROUP BY ID
,Product
FOR JSON PATH;
The issue is QUOTENAME input is limited to 128 chars and returns NULL when you add more records.